Previously, many types of filters have been used in endeavoring to provide an effective means for the separation of parasite eggs and larvae from feces samples. Over the years, many types of devices have been developed to concentrate parasitic eggs and larvae also protozoan cysts and to recover coccidian occysts such as isospora belli and cryptosporidium parvium.
A search of the prior art did not disclose any patents that read directly on the claims of the instant invention, however the following U.S. patents are considered related:
______________________________________ PATENT NO. INVENTOR ISSUED ______________________________________ 4,081,356 Zierdt 23 March 1978 4,675,110 Fay 23 June 1987 ______________________________________
The U.S. Pat. No. 4,081,356 Zierdt discloses a current device and method for recovering parasitic eggs and larvae from feces samples. In this device, a cup is attached to an open ended tube forming an emulsification chamber. A filter is attached to the chamber which includes a coaxial tube for the passage of air and a centrifuge tube is attached by an annular collar to form a separating chamber. Zierdt also teaches a method which includes: the adding of liquids to dilute the sample, mechanical stirring, shaking and straining to separate the sediment containing eggs and larvae, and decanting the supernatant fluid after centrifuging. This process utilizes a separate filter using a metal or plastic 30 mesh screen. The gas passage tube, which has a 0.1 inch outside diameter and a 0.06 inside diameter is located in the center of the filter and leaves much to be desired as it is easily clogged and blocked by debris. Further, the double ended cap is expensive and unnecessarily complicated.
The U.S. Pat. No. 4,675,110 Fay discloses a device and method for the concentration of parasite eggs and larvae. The device consists of separable upper and lower chambers connected by a mid-piece which incorporates a filter of stainless steel gauze. The sample is emulsified in the upper chamber and is filtered into the lower chamber. Ether is added to the upper chamber, and the mid-piece and upper chamber are removed. The lower chamber is then shaken and centrifuged, the mid-plug of debris is removed, and the tube is drained and swabbed clean leaving a small sediment containing the sediment containing the parasite eggs and larvae. The sediment is removed by extraction with Lugol's iodine or saline to dilute the sediment. The filter used in this device is relatively complex and expensive. Also, the Fay device utilizes a number of gas return passages which are arranged around the exterior of the filter insert and which create multiple apertures. These apertures, function to equalize pressure between the chambers however, it nonetheless requires frequent agitation to clear the passage of undigested vegetable matter and other debris. Further, separate tooling is required for each piece obviously affecting the overall cost of the device which is disposed of after use.
Other systems and methods have been utilized for the same purpose such as the fecal parasite, concentrator known by its registered trademark FPC and JUMBO and manufactured by Evergreen Scientific of Los Angeles, Calif. The JUMBO concentrator functions in the same manner as described above and connects a vial and tube together as with Fay's teachings. A movable vent-straw is located in the center of the strainer unit and requires manually pulling the straw out approximately 1.0 inch (2.54 cm) prior to attachment of the specimen vial. The problems of clogging and blocking the pressure equalizing element still exist and multiple components are employed.
For background purposes and as indicative of the art to which the invention relates reference may be made to the remaining cited patents.
______________________________________ PATENT NO. INVENTOR ISSUED ______________________________________ 4,439,319 Rock 27 March 1984 4,555,336 Nugent et al 26 November 1985 4,722,792 Miyagi et al 2 February 1988 4,769,145 Nakajima 6 September 1988 4,824,560 Alspector 25 April 1989 4,832,851 Bowers et al 23 May 1989 4,956,103 Jessop et al 11 September 1990 5,108,381 Kolozsi 28 April 1992 5,208,161 Saunders et al 4 May 1993 5,244,635 Rabson et al 14 September 1993 5,252,460 Fiedler et al 12 October 1993 5,254,314 Yu et al 19 October 1993 5,256,314 Driessen 26 October 1993 5,277,873 Hsei 11 January 1994 5,283,038 Seymour 1 February 1994 5,308,483 Sklar et al 3 May 1994 5,316,732 Golukhov et al 31 May 1994 5,318,748 Babson et al 7 June 1994 5,330,916 Williams et al 19 July 1994 5,356,814 Carrico, Jr. et al 18 October 1994 ______________________________________